Speed of system memory is a determining factor for further performance of a computer system. The most common form of system memory installed today is synchronous dynamic random access memory (SDRAM). A computer system's memory is a temporary storage area for data that needs to be available for programs to run efficiently. The faster the system memory can provide data, the more work the computer system's central processing unit (CPU) can perform. Increased data throughput between memory and CPU via memory busses or memory channels translates directly into better system performance.
However, increasing memory bandwidth by increasing the speed of a memory channel is sometimes leads to a reduced number of memory module slots or sockets per memory channel due to signal integrity problems, thus limiting the maximum memory density, i.e., the number of memory module slots, that can be used with a given number of memory channels. The number of memory channels connected to a memory controller or to a CPU is in some cases limited due to a limited number of data pins of the memory controller or the CPU.
On the other hand, due to increasing multi-core architecture of CPUs and virtualization, there is an increasing need for both, memory bandwidth and memory density in the future. These two features are, however, limiting each other.